This study will examine the relationship between tooth wear, enamel structure, and the potential for fracture in bunodont teeth. Tooth fracture is a common clinical problem, and the results of this study will contribute to our understanding of how the design and function of human teeth are related to tooth fracture potential. Tensile forces are likely to cause fracture in brittle materials and understanding the location and intensity of these forces in the enamel is critical to determining the potential for fracture. The results of this study will differentiate between two hypotheses: l) that tooth cusp tip wear increases the probability of fracture in bunodont teeth by changing the intensity of tensile stresses in the enamel and that cusp tip preservation is vital to the 'safe' conduction of stresses through the enamel cap, or 2) that cusp tip wear may actually reduce the probability of enamel fracture by decreasing or redistributing the tensile stresses. Study of enamel strain during tooth loading will determine how stresses are conducted through the enamel differently as enamel cusp tip wear proceeds and as the material properties of food change. Strain gauges will be affixed to the buccal surface of fetal pig molars at different stages of cusp tip wear. Strain gauge recordings will be made during masseter muscle stimulation and tooth biting on hard and soft foods. Scanning electron and light microscopy of enamel architecture among the bunodont molars of pigs and carnivores will determine if there is a consistency between stress-related aspects of the enamel structure and the distributions of stresses as cusp wear proceeds. The combined results will determine how tooth wear and enamel structure affect the location and intensity of tensile forces in the enamel cap.